NaP zeolite particles were prepared through a template-free hydrothermal condition at 100oC. Parameters like Na2O/Si O2 and Si O2/Al2O3 molar ratios, gel aging time and aging temperature were investigated for regulati...NaP zeolite particles were prepared through a template-free hydrothermal condition at 100oC. Parameters like Na2O/Si O2 and Si O2/Al2O3 molar ratios, gel aging time and aging temperature were investigated for regulating the crystallization of the final product. The samples at different synthesis stages were characterized with N2 adsorption at-196oC, field emission scanning electron microscopy(FE-SEM), temperature programmed desorption of ammonia adsorption, X-ray diffraction, thermogravimetric and differential scanning calorimetry analysis and Fourier transform infrared spectroscopy. The experimental results evidenced that a high ordering crystallinity of Na P zeolite was obtained at Na2O/Si O2 and Si O2/Al2O3 molar ratios of 1.10 and 1.40, respectively, and a temperature of 100°C for 4 days of aging. FE-SEM image exhibited polycrystalline aggregates of Na P zeolite with crystallite sizes ranging up to 5.04 μm with cactus/cabbage like structures. The quantitative analysis of the total number of acid sites was found to increase as Na2 O increases. The Na P zeolite sample with a Na2O/Si O2 molar ratio of 1.13 exhibited a large fraction of the acid sites on its external surface, contrary to that synthesized with a relevant ratio of 1.10. The optimized Na P zeolite could be successfully bestowed with excellent sorption properties of Ca(II) in aqueous solution. The kinetic parameters for Ca(II) adsorption were thoroughly investigated.展开更多
文摘NaP zeolite particles were prepared through a template-free hydrothermal condition at 100oC. Parameters like Na2O/Si O2 and Si O2/Al2O3 molar ratios, gel aging time and aging temperature were investigated for regulating the crystallization of the final product. The samples at different synthesis stages were characterized with N2 adsorption at-196oC, field emission scanning electron microscopy(FE-SEM), temperature programmed desorption of ammonia adsorption, X-ray diffraction, thermogravimetric and differential scanning calorimetry analysis and Fourier transform infrared spectroscopy. The experimental results evidenced that a high ordering crystallinity of Na P zeolite was obtained at Na2O/Si O2 and Si O2/Al2O3 molar ratios of 1.10 and 1.40, respectively, and a temperature of 100°C for 4 days of aging. FE-SEM image exhibited polycrystalline aggregates of Na P zeolite with crystallite sizes ranging up to 5.04 μm with cactus/cabbage like structures. The quantitative analysis of the total number of acid sites was found to increase as Na2 O increases. The Na P zeolite sample with a Na2O/Si O2 molar ratio of 1.13 exhibited a large fraction of the acid sites on its external surface, contrary to that synthesized with a relevant ratio of 1.10. The optimized Na P zeolite could be successfully bestowed with excellent sorption properties of Ca(II) in aqueous solution. The kinetic parameters for Ca(II) adsorption were thoroughly investigated.
